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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Invertase formation in the yeast Saccharomyces cerevisiae is subject to repression by hexoses in the growth medium. Mutagen-induced (ethyl methanesulfonate or N-methyl-N-nitro-nitrosoguanidine) invertase hyperproducer mutants have been derived from the SUC3 MAL3 strain EK-6B by selecting for their ability to grow on media containing the sugar raffinose plus 2-deoxy-D-glucose (2DG). Raffinose like sucrose is a betta-fructoside which can be hydrolyzed by yeast invertase (beta-fructoside which can be hydrolyzed by yeast invertase (beta-fructofuranoside fructohydrolase). These mutants, designated dgr, produce higher levels of invertase (pi-glucosidase levels are also elevated but to a lesser extent) under conditions normally repressing invertase biosynthesis in the parent. Invertases of mutants dgr2 and dgr3 are indistinguishable from that of EK-6B with respect to their Km's for sucrose and thermal labilities. Genetic studies revealed that dgr2 and dgr3 are recessive and unlinked to the SUC3 gene.
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PMID:Genetic control of invertase formation in Saccharomyces cerevisiae. II. Isolation and characterization of mutants conferring invertase hyperproduction in strain EK-6B carrying the SUC3 gene. 36 57

We report here on the molecular nature of an EMS-induced mutant, mn1-89, a leaky semidominant allele of the Miniature1 (Mn1) seed locus that encodes a seed-specific cell wall invertase, INCW2. The mn1-89 locus specifies normal levels of the Incw2 transcript but extremely low levels (about 6% of normal) of the protein and enzyme activity are expressed. Sequence analysis of Incw2 clones derived from the parental Mn1 and the mutant genotypes shows a C to T transition in the mn1-89 allele, leading to a single amino acid alteration (proline to leucine) near the C-terminus of the mutant INCW2 protein. Although this change is not in the catalytic domain, putative N-glycosylation sites, or the beta-fructosidase motif, it does lie in a motif that is well conserved among all plant invertases and related fructosyltransferases. On the basis of these genetic in planta data, we believe we have identified a proline residue in a hitherto unknown GPFG motif as critical for the stability of such proteins. The single base change (C to T) also leads to the elimination of a BglI restriction site in the mutant allele. Indeed, BglI restriction digests of genomic DNAs from mn1-89 and Mn1 genotypes show one and two fragments, respectively. Sequence analysis of RT-PCR-derived endosperm Incw clones from mn1-1 (the reference allele) seeds predict five amino acid substitutions relative to Mn1. Whether or not these sequences are encoded by the mn1-1 locus or another non-allelic Incw gene in the maize genome remains to be elucidated.
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PMID:A point mutation at the Miniature1 seed locus reduces levels of the encoded protein, but not its mRNA, in maize. 1077 57

Collective evidence demonstrates that the Miniature1 (Mn1) seed locus in maize encodes an endosperm-specific isozyme of cell wall Invertase, CWI-2. The evidence includes (1) isolation and characterization of ethyl methanesulfonate-induced mn1 mutants with altered enzyme activity and (2) a near-linear relationship between gene/dose and invertase activity and the CWI-2 protein. In addition, molecular analyses showed that the cDNA clone incw2 maps to the Mn1 locus and differentiates the six ethyl methanesulfonate-induced mn1 mutants of independent origin into two classes when RNA gel blot analyses were used. We also report two unexpected observations that provide significant new insight into the physiological role of invertase and its regulation in a developing seed. First, a large proportion of total enzyme activity (~90%) was dispensable (i.e., nonlimiting). However, below the threshold level of ~6% of wild-type activity, the endosperm enzyme controlled both the sink strength of the developing endosperm as well as the developmental stability of maternal cells in the pedicel in a rate-limiting manner. Our data also suggest an unusually tight coordinate control between the cell wall-bound and the soluble forms of invertase, which are most likely encoded by two separate genes, presumably through metabolic controls mediated by the sugars.
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PMID:The Miniature1 Seed Locus of Maize Encodes a Cell Wall Invertase Required for Normal Development of Endosperm and Maternal Cells in the Pedicel. 1223 8

A short root mutant was isolated from an EMS-generated rice mutant library. Under normal growth conditions, the mutant exhibited short root, delayed flowering, and partial sterility. Some sections of the roots revealed that the cell length along the longitudinal axis was reduced and the cell shape in the root elongation zone shrank. Genetic analysis indicated that the short root phenotype was controlled by a recessive gene. Map-based cloning revealed that a nucleotide substitution causing an amino acid change from Gly to Arg occurred in the predicted rice gene (Os02g0550600). It coded an alkaline/neutral invertase and was homologous to Arabidopsis gene AtCyt-inv1. This gene was designated as OsCyt-inv1. The results of carbohydrate analysis showed an accumulation of sucrose and reduction of hexose in the Oscyt-inv1 mutant. Exogenously supplying glucose could rescue the root growth defects of the Oscyt-inv1 mutant. These results indicated that OsCyt-inv1 played important roles in root cell development and reproductivity in rice.
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PMID:OsCYT-INV1 for alkaline/neutral invertase is involved in root cell development and reproductivity in rice (Oryza sativa L.). 1831 96